CN105203606B - A kind of preparation method and applications based on copper metal organic frame complex modified gold electrode - Google Patents

Abstract

The present invention discloses a kind of preparation method and applications based on copper metal organic frame complex modified gold electrode, is prepared using hydro-thermal method, steps are as follows: 1) preparing cupric coordination compound { [CuL (H2O)] 0.5DMA }；2) preparation of { [CuL (H2O)] 0.5DMA } metallic organic frame complex modified electrode；3) modified electrode for detecting l-methionine and D-Met respectively.The invention has the advantages that the present invention is prepared for metallic organic frame complex { [CuL (H2O)] 0.5DMA } for the first time, and structural characterization is carried out to it, it is prepared for { [CuL (H2O)] 0.5DMA } modification novel electrochemical sensor, the detection applied to l-methionine and D-Met chiral isomer.Modified electrode preparation is simple, cheap, has significant technical effect.

Description

A preparation method for modifying gold electrodes based on copper metal-organic framework complexes and its application

technical field

The present invention relates to a preparation method based on a copper metal organic framework complex and a modified electrode based on this substance, as well as the detection of chiral isomers of D-methionine and L-methionine technology.

Background technique

Methionine, also known as methionine, is a sulfur-containing essential amino acid. Methionine is closely related to the metabolism of various sulfur-containing compounds in the organism. The organism must convert the D-form into the L-form in the body before it can be used by the body. It is widely used in many fields such as feed, food, medicine, agriculture and environmental monitoring. How to efficiently and accurately realize the detection and identification of chiral isomers of methionine is an urgent problem to be solved now.

In recent years, metal-organic frameworks (MOFs) have attracted widespread attention in the chemical community due to their unique porous structures, diverse coordination modes, and their applications in energy, electrochemistry, catalysis, adsorption, and energy storage. In the field of electrochemistry, researchers have found that various substances can be electrochemically detected by modifying MOF materials on the electrode surface. For example, Diana M et al. used Pmo ₁₂ V ₂ @MIL-101(Cr) porous modified electrodes to realize dopamine and ascorbic acid. Synchronous detection; HadiHosseini et al. researched and developed Au-SH-SiO ₂ @Cu-MOF electrochemical sensor and applied it to the electrocatalytic oxidation of L-cysteine, and achieved good results. Therefore, MOF materials have potential application prospects in the field of electrochemistry. However, studies have found that only a few MOF materials have electronic conductivity, which limits the promotion and application of MOF materials in the field of electrochemistry.

Contents of the invention

The purpose of the present invention is to solve the above-mentioned difficult problems, to provide a method for preparing a novel metal-organic framework complex, to prepare a novel electrochemical sensor using the metal framework complex, and to apply it to D-methionine Electrochemical recognition of acid and L-methionine.

Technical scheme of the present invention:

A method for preparing a gold electrode modified based on a copper metal organic framework complex, which is prepared by a hydrothermal method, and the steps are as follows:

1) Synthesis of metal-organic framework complex Cu-MOF{[CuL(H ₂ O)]·0.5DMA}:

Prepare stock solution A by dissolving 0.2 mmol of copper chloride dihydrate in 2 mL of distilled water, and prepare by adding 0.2 mmol of thiophene-2,5-dicarboxylic acid (H ₂ L) into 2 mL of N,N-dimethylacetamide Prepare stock solution B, then mix stock solution A with stock solution B, place in an oven at 90°C for 48 hours, filter after natural cooling, and wash the obtained solid with distilled water 2-6 times to obtain a blue crystalline solid metal organic framework complexes;

2) Preparation of {[CuL(H ₂ O)]·0.5DMA} complex modified electrode:

Weigh 0.25g of chitosan, dissolve it in 100mL of 1% acetic acid aqueous solution to obtain a clear, uniform and transparent stock solution C, weigh 0.020g of {[CuL(H ₂ O)]·0.5DMA} complex, add In the above C, a light green suspension was obtained, and 10 μL of the suspension was spotted on the surface of a clean glassy carbon electrode, and dried naturally for 12 hours to obtain a {[CuL(H ₂ O)]·0.5DMA} modified electrode.

The present invention also provides an application based on copper metal organic framework complex modified gold electrode, that is, its detection technology in D-methionine and L-methionine chiral isomers:

Detection of D-methionine and L-methionine:

The {[CuL(H ₂ O)]·0.5DMA} modified electrode was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the platinum wire electrode was used as the auxiliary electrode to form a three-electrode system. The solution (pH=6.8) was tested separately for D-methionine and L-methionine.

The phosphate buffer solution is prepared by mixing sodium dihydrogen phosphate (0.2 mol/L) aqueous solution and disodium hydrogen phosphate aqueous solution (0.2 mol/L). The pH was determined by a pH meter.

The advantages of the present invention are: the present invention firstly prepared the metal organic framework complex {[CuL(H ₂ O)]·0.5DMA}, carried out structural characterization on it, prepared {[CuL(H ₂ O)]·0.5 DMA} modified novel electrochemical sensor, applied to the detection of D-methionine and L-methionine. The modified electrode is simple to prepare, low in price, and has remarkable technical effects.

Description of drawings

Fig. 1 is a molecular structure diagram obtained from the single crystal X-ray diffraction analysis of {[CuL(H ₂ O)]·0.5DMA}.

Fig. 2 is a comparison chart of powder X-ray diffraction pattern of {[CuL(H ₂ O)]·0.5DMA} and single crystal simulation data.

Figure 3 shows the detection of D-methionine by the {[CuL(H ₂ O)]·0.5DMA} modified electrode.

Fig. 4 is the detection of L-methionine by the {[CuL(H ₂ O)]·0.5DMA} modified electrode.

Detailed ways

The present invention is based on a method for preparing a gold electrode modified by a copper metal organic framework complex, which is prepared by a hydrothermal method, and the steps are as follows:

1) Synthesis of Metal Organic Framework Complex {[CuL(H ₂ O)]·0.5DMA}

Weigh 0.0341g CuCl ₂ 2H ₂ O and dissolve it in 2mL distilled water to prepare stock solution A. Weigh 0.0344g thiophene-2,5-dicarboxylic acid and add it to 2mL N,N-dimethylacetamide to prepare Stock solution B, then mix stock solution A with stock solution B, place in a closed container, place in an oven at 90°C for 48 hours, cool down for 48 hours, filter the obtained solid, wash 2-6 times with distilled water to obtain The light green crystal is the metal-organic framework complex {[CuL(H ₂ O)]·0.5DMA};

Characterization of the properties of the metal organic framework complex {[CuL(H ₂ O)]·0.5DMA}:

(1) Determination of single crystal structure

Crystal structure The crystal structure was determined using a Supernova type X-ray single crystal diffractometer, using Mo Kα rays that have been monochromated by graphite is the incident radiation source, with The diffraction points were collected by scanning, and the unit cell parameters were corrected by the least square method. The crystal structure was solved by the SHELXL-97 direct method from the difference Fourier electron density map, and corrected by Lorentz and polarization effects. All H atoms were synthesized by difference Fourier and determined by ideal position calculation. The crystal determination data are shown in Table 1

Table 1 Crystallographic data of compounds

Fig. 1 is a diagram of the smallest structural unit obtained from the single crystal diffraction analysis of the compound {[CuL(H ₂ O)]·0.5DMA}. It can be seen from the diagram that the compound molecule contains a copper ion and a dehydrogenation ligand L ^- , A coordinated water and free solvent molecule DMA. The occupancy ratios of Cu1 and Cu2 are 0.5, respectively.

(2) Powder X-ray Diffraction Determination:

The powder X-ray diffraction data were collected on a Rigaku D/Max-2500 diffractometer with an operating voltage of 40kV and a current of 100mA. The copper target X-ray monochromated by graphite was used as the incident radiation source in the test. Density data collection uses 2θ/θ scanning mode, continuous scanning in the range of 3° to 60°, the scanning speed is 8°/second, and the span is 0.02°/time. The experimental data were fitted using the Cerius2 program, and the single crystal structure powder X-ray diffraction spectrum was simulated and transformed using the software Mercury 1.42.

Fig. 2 is a powder X-ray diffraction diagram of the {[CuL(H ₂ O)]·0.5DMA} complex compared with a simulation diagram based on single crystal data.

2) Preparation of {[CuL(H ₂ O)]·0.5DMA} complex modified electrode:

Weigh 0.25g of chitosan and dissolve it in 100mL of 1% acetic acid aqueous solution to obtain a clear, uniform and transparent stock solution C. Weigh 0.020 g of the {[CuL(H ₂ O)]·0.5DMA} complex and add it to the above C under ultrasonic conditions to obtain a light green suspension. Take 10 μL of the suspension and spot it on the surface of a clean glassy carbon electrode, and let it dry naturally for 12 hours to obtain a {[CuL(H ₂ O)]·0.5DMA} modified electrode.

The obtained {[CuL(H2O)] 0.5DMA} complex modified gold electrode of the present invention can be used for the detection of L-methionine and D-methionine, and the detection method is as follows:

(1) Detection of L-methionine at {[CuL(H ₂ O)]·0.5DMA} complex modified electrode:

The metal-organic framework complex {[CuL(H ₂ O)]·0.5DMA} modified electrode was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the platinum wire electrode was used as the auxiliary electrode to form a three-electrode system. Enter the electrochemical workstation, and detect L-methionine in phosphate buffer solution (pH=6.8). The modified electrode has a good response to L-methionine, as shown in Figure 3.

(2) Detection of D-methionine at {[CuL(H ₂ O)]·0.5DMA} complex modified electrode:

The metal-organic framework complex {[CuL(H ₂ O)]·0.5DMA} modified electrode was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the platinum wire electrode was used as the auxiliary electrode to form a three-electrode system. into an electrochemical workstation, and detect D-methionine in a phosphate buffer solution (pH=6.8). The modified electrode has a good response to D-methionine, as shown in Figure 4.

Claims (2)

1. a kind of application based on copper metal organic frame complex modified electrode, it is characterised in that: for molten in phosphoric acid buffer In liquid, completion detects D-Met or l-methionine,

It is as follows to the detecting step of l-methionine:

By metallic organic frame complex obtained { [CuL (H₂O)] 0.5DMA } for modified electrode as working electrode, saturation is sweet Mercury electrode forms three-electrode system as auxiliary electrode, electrochemical workstation is accessed, in phosphorus as reference electrode, platinum electrode Acid buffering solution detects l-methionine；

It is as follows to the detecting step of D-Met:

By metallic organic frame complex obtained { [CuL (H₂O)] 0.5DMA } for modified electrode as working electrode, saturation is sweet Mercury electrode forms three-electrode system as auxiliary electrode, electrochemical workstation is accessed, in phosphorus as reference electrode, platinum electrode Acid buffering solution detects D-Met；

Wherein metallic organic frame complex { [CuL (H₂O)] 0.5DMA } modified electrode is prepared by the following preparation method, it walks It is rapid as follows:

1) metallic organic frame complex { [CuL (H₂O)] 0.5DMA } synthesis:

Copper dichloride dihydrate is dissolved in distilled water and is prepared into stock solution A, 2,5-ThiophenedicarboxyliAcid Acid is added to N, N- dimethyl It is prepared into stock solution B in acetamide, then mixes stock solution A with stock solution B, is placed in 90 DEG C of baking oven and reacts 48 hours, It is filtered after Temperature fall, obtained solid is washed with distilled water 2-6 times, obtain blue crystalline solid metal organic frame cooperation Object；

2){[CuL(H₂O)] 0.5DMA } complex decorating electrode preparation:

0.25g chitosan is weighed, is dissolved in the aqueous acetic acid of 100mL1%, limpid homogeneous and transparent stock solution C is obtained, weighs 0.020g{[CuL(H₂O)] 0.5DMA } complex, it is added in above-mentioned C under ultrasound condition, obtains jade-green suspension, take For the 10 μ L suspension point in clean glassy carbon electrode surface, 12 hours naturally dries obtain { [CuL (H₂O)] 0.5DMA } it repairs Adorn electrode；

Copper chloride dihydrate described in step 1), thiophene -2,5- dicarboxylic acids molar ratio be 1:1；Distilled water and N, N- dimethyl second The volume ratio of amide is 1:1；The Copper dichloride dihydrate is 0.2mmol, and the distilled water is 2mL, thiophene -2,5- dicarboxyl Acid is 0.2mmol, and the n,N-dimethylacetamide is 2mL.

2. the application according to claim 1 based on copper metal organic frame complex modified electrode, it is characterised in that: phosphorus Acid buffering pH value of solution=6.8.